hi there,

i'm encountering a strange behavior of my kubuntu 16.04 system since few days, i think after some ordinary system upgrade using sudo apt update/upgrade.

1) the bottom panel (task bar) as well as the starter menu turned from very light to very dark gray, although, i haven't changed any display or other system settings

2) simultaneously, several popup menus do not appear any more, e.g. those associated with browser plugins/addons such as the addblockplus symbol in the upper right area of firefox, or info text when hovering over images/links/etc. of websites.

does anyone have a useful hint?

many thanks in advance,

fred

Have you rebooted since the updates (or at least logged out and back in)?
Depending on the nature of the update you usually need to at least relaunch any apps that were updated. Occasionally updates include changes which require shutting down the whole system in order to fully take effect.

If the problem persists after restarting, you may also try creating a new user and see if the problem affects the new user or not (this will indicate if the problem is in the system itself or with user-specific configuration).

thanks airdrik. the problem resisted. but i was suggested a solution on a german site: activating xrender (instead of openl) did the trick ..